Aluminum head piston



July 29, 1930. J, QAMPBELL 1,771,771

ALUMINUM HEAD PIS TON Fi led June 20, 1927 2 Sheets-Sheet 1 il m Donald 6. CompQelL flffw/x Juiy 29, 1930. D. J. CAMPBELL ALUMINUM HEAD PISTON 2 Sheets-Sheet 2 Filed June 20, 1927 lnuenTor Donald d. Campbell Patented July 29, 1930 PATENT OFFICE DONALD J. CAMPBELL, F MUSKEGON, MICHIGAN ALUMINUM HEAD PISTON Application filed June 20,

This invention relates to a composite piston, that is, a piston which is constructed of cast iron and aluminum. It is an object and purpose of the present invention to construct a piston having a cast iron lower part with integral bosses for mounting the wrist pins which connect the piston with the connecting rod, and to provide the piston with an aluminum head which is securely connected to the cast iron part of the piston and interlocked therewith so that it cannot become loose. The cast iron part is provided at its upper end where'the aluminum head is attached with supporting ribs or cross bars for the aluminum head to strengthen and reinforce the head of the piston in order that it may withstand the explosion shocks to which it is subjected. My invention consists of many novel details of construction and arrangements ofparts for producing a novel, practical and eflicient piston of the character described.

An understanding of the invention may be had from the following description taken in connection with the accompanying drawings, in which,

Fig. 1 is an elevation of the piston, certain parts thereof being broken away and shown in section for a better disclosure of the interior construction.

Fig. 2 is a vertical section taken substantially on the plane of line 22 of Fig. 3, the section being taken through the complete piston with the head attached.

Fig. 3 is a plan View of the lower cast iron portion of the piston, and

Fig. 4 is a side elevation thereof.

Like reference characters refer to like 7 parts in the different figures of the drawings. In the construction of the piston a skirt 1 of cast iron is used from which at opposite sides wrist pin bosses 2 extend inwardly being formed integrally with the skirt portion of the piston. A short distance above the plane of the wrist pins a downwardly and inwardly inclined annular shoulder 3 is made .and a short distance above it a second horizontal shoulder 4 is formed, the metal extending upwardly from the inner side of said 0 shoulder in an annular ring 5. At the outer 1927. Serial No. 199,927.

side of the ring 5 a plurality of spaced apart dove tailed projections 6 are made which have side edges converging toward their lower ends and which are also undercut. This makes a plurality of dove tailed grooves 7 between the projections 6 as best shown in Figs. 3 and 4.

Extending across the open upper end of the ring 5 are cross bars 8, there being shown four of the cross bars radiating from the central axis of the piston integrally connected at their inner ends and joining with the ring portion 5 at their outer ends and with reinforcing vertical ribs 9 which extend vertically downward at the outer ends of the bars 8, said ribs at the ends of two of the radiating bars integrally joining with the upper sides of the wrist pin bosses 2. Where the bars 8 come together at the center of the piston the same are formed at their upper sides with upwardly extending enlargements 10 for a portion of their length which have undercut sides so that the enlargements 10 are wider at their upper sides than where they join the bars 8. The aluminum head 11 of the piston is cast over the upper end of the cast metal structure described, the melted aluminum flowing into the grooves 7 around the dove tailed projections 6 and around the undercut sides and ends of the enlargements 10 on the bars 8, filling all of the recesses and making a firm and secure interlock of the aluminum head with the cast iron member of the piston. The head 11 may be equipped with the usual ring grooves 12 common in pistons in internal combustion engines.

A piston made as described attains all of the advantages of cast iron, particularly in the bearings for the wrist pin, while the aluminum head conducts heat from the burning or exploding of gaseous charges rapidly to the piston rings and thence to the walls of the cylinder. The iron is less rapid in its conduction of heat and the heat from the burning or exploding gases will not be trans mitted to the interior of the piston and to the lubricant below in :the crank case of the engine in which the piston is installed. The dove tailed projections and grooves 6 and 7 and the dove tailed formation of the enlarge-v ments 10 of the bars 8 make a very firm and strong interlock of the aluminum head to the cast iron member of the piston such that there is no possibility of disconnection 01' even loosening of the head with respect to the cast iron member. In addition the piston is lightened in weight, this being a desirable feature of pistons in internal combustion engines.

The invention is defined in the appended claims and is to be considered comprehensive of all forms of structure coming within their scope.

I I claim:

1. A piston comprising, a skirt of cast iron, wrist pin. bosses integral with said skirt and an upwardly extending ring of smaller diameter than the skirt located at the upper end of the cast iron portion of the piston, said ring having spaced apart dove tailed projections at its sides wider at their upper than at their lower ends, and an aluminum head over the cast iron part of the piston having depending sides around said ring and covering said dove tailed projections and filling the spaces therebetween.

2. A composite piston comprising, an upper head of aluminum and a lower part of cast iron, said cast iron part having dove tailed projections at its sides adjacent its upper end around and over which the aluminum head is cast.

3. A composite piston comprising, a lower skirt of cast iron having a portion at the upper end thereof of less diameter than the diameter of the skirt, integral bars extend across the upper end of the cast iron part of the piston and provided with rupwardly interlocking with the dove tailed projections on said ring.

5. A piston comprising, an aluminum head having depending sides, and a cast iron skirt having an integral upper end portion located within the depending sides of the piston, interlocking connections between said depending sides of the head and-said portion of the cast iron piston around which it is located, integral bars extendin across the upper end of the cast iron part 0 the piston and underneath the top of said aluminum head, and interlocking connections between said bars and the top of said head.

6. A pistoncomprising, a cylindrical skirt open at its upper end, integral bars across the upper end of the skirt, interlocking members on said bars, an aluminum head cast over the upper end of the skirt and over said bars, and said interlocking members thereon, the inner and outer surfaces of said skirt being exposed.

In testimony whereof I aifix my signature.

DONALD J. CAMPBELL.

extending projections wider at their upper sides than where they join said bars, and an aluminum head cast over the upper end of the cast iron part of the piston having depending'sides surrounding the smaller upper end of the cast iron part of the piston and interlocking with the projections on said barsj integral wrist pin bosses formed therewith, a ring of less diameter than the skirt formed 4. A piston'comprising, a skirt of cast iron,

integral therewith at the upper end thereof,

radially located bars formed integral with saidring and extending horizontally across the upper end thereof, projections wider at their upper sides than where they join said barsprojecting upwardly from said bars, dove tailed projections extending from the outer vertical sides of said ring in spaced apart relation to each other, said projections being'wider at their upper than at their lower ends, and a head of aluminum cast over said ring and bars and interlocking with the rojections thereon, said head having de- "pen ing sides lying in substantially the same planes with the outer sides ofthe skirt, and 

